The objective of this proposal is the further development of a multifaceted research program for studying the biochemical mechanisms of action, and the molecular basis of resistance to antitumor drugs. Initially, bleomycin and taxol will be the drugs used in our research program which includes a) in vitro biochemical studies to investigate the interaction of bleomycin with DNA and the binding of taxol to microtubules; b) preparation of radiolabeled bleomycin and taxol; c) the uptake, efflux and metabolism of these drugs in cells; d) preparation of antibodies to taxol to be used for immunofluorescent localization of the drug and radioimmunoassays; e) the preparation, transport into cells and analysis of drug-tumor specific monoclonal antibody complexes; and e) studies with new natural compounds related to taxol and synthetic taxol analogs to develop structure-activity relationships for improving the solubility and therapeutic activity of the drug. In addition, the effects of drugs are being studied in the macrophage- like cell line J774 in which functions such as phagocytosis and migration can be quantitated. Sublines of the J774 cell line that are resistant to the growth inhibitory properties of taxol and bleomycin have been isolated and are being analyzed for macrophage function, biochemical abnormalities, karyotype, cross resistance or hypersensitivity to other drugs and alterations in drug uptake. These variants plus others that are resistant to the growth-inhibitory effects of colchicine and vinblastine have double minute chromosomes. The membranes of each of these sublines contain a unique phosphoglycoprotein that is not present in the parental cell line. Studies on the biosynthesis, purification, localization and function of the phosphoglycoproteins are proposed. Antibodies prepared against the phosphoglycoprotein will be used for isolation of specific mRNA. The presence of amplified DNA sequences and their location will be probed. New drugs, preferably with unique structures, will be added to our program as will a variety of new drug-resistant cells.